How can I raise a Warlock Vigilante mystic bolt's damage?

Question

As a Vigilante with the Warlock archetype, is there any possible way to raise the damage of the Mystic Bolt other than a raise in level?

I'm open to any Paizo feats, items, traits or basically anything you can think of.

Answer 1

Anything that can increase the damage of light one-handed weapons.

From the description of Mystic Bolts:

The warlock vigilante attacks with mystic bolts as though they were light one-handed weapons, and the bolts can be used for two-weapon fighting (with each hand creating one mystic bolt) and feats and abilities that apply to weapon attacks (unless they’re excluded from that feat, such as with Power Attack).

The list is pretty vast, but goes from Point Blank Shot, to Rapid Shot, to Weapon Specialization. It also includes your Favored Enemy and Sneak Attacks.

Exceptions

The exception mentioned on Power Attack is a hint of what could work or not for your bolts:

The bonus damage does not apply to touch attacks or effects that do not deal hit point damage.

This will obviously also exclude effects that call for a particular type of one-handed light weapons, such as natural weapons or manufactured weapons. If a feat says that it increases your damage with one-handed light weapons it will apply to your bolts, but if it says one-handed light manufactured weapon it won't, because the bolts are not of the type manufactured from their description.

If the effect lists any special subtype of weapons, they do not apply to your bolts, such as:

• Simple one-handed light weapons
• Martial one-handed light weapons
• Ranged one-handed light weapons
• Exotic one-handed light weapons
• Throwing one-handed light weapons
• Natural light weapons
• Manufactured weapons, which are not properly defined by the rules. But it's worth noting that Haste has several FAQs about it, and the developers have acknowledged that mystic bolts should work with haste, despite not being a manufactured or natural weapon.
• Technological weapons

Answer 2

Unfortunately, thanks to this FAQ, damage from Mystic Bolts takes a huge hit from never getting an ability score to damage, regardless of how you use them. This FAQ also specifies that the Mystic Bolts do not count as manufactured weapons, which causes them to not work with many of the usual options (Haste, Sense Vitals, etc).

EDIT: There's another FAQ that explicitly states that, despite not counting as a manufactured weapon, you can still benefit from the extra attack from Haste with Mystic Bolts.

That said, there are still many effects that can be used to add damage to them. As a small sample, you could use:

• Unchained Barbarian Rage - morale bonus to hit and damage
• Arcane Strike - bonus damage, scaled by caster level
• Weapon Specialization (and Greater) - bonus to damage
• Deliquescent Gloves - add 1d6 acid damage
• Demonic Smith's Gloves - add 1d6 fire damage
• Divine Favor - specifically useful for a Warpriest's Fervor ability, luck bonus to hit and damage, scaled by caster level (also use the trait Fate's Favored for an extra bonus)
• Warpriest's Sacred Weapon - increased damage die, scaled by level
• Sneak Attack - extra damage dice against flanked or flatfooted enemies (with options for extra damage, like Accomplished Sneak Attacker and Blade of the Society)
• Precise Strike, Teamwork - teamwork feat for extra damage dice while flanking
• Slayer's Studied Target - bonus to hit and damage against studied enemy (also available for Sanctified Slayer Inquisitor)
• Power Attack/Deadly Aim/Piranha Strike - a nice boost to damage, but only works if you opt not to use the Mystic Bolts as touch attacks
• Point Blank Shot - bonus to hit and damage within 30ft
• Hammer the Gap - bonus damage for consecutive hits (can be a lot thanks to Mystic Bolts working with both Two-Weapon Fighting and Rapid Shot)
• Weapon Master Fighter's Weapon Training - bonus to hit and damage
• Bard's Inspire Courage - scaling competence bonus to hit and damage (extra good with Dawnflower Dervish archetype for double bonuses and Singing Steel armor to make it a swift action)

Again, this is just a small sample. These are just some of the ways to add extra damage to the Mystic Bolts.

Answer 3

If you're open to 3pp material, the book Legendary Villains: Vigilantes has a few feats that make Mystic Bolts viable. Namely the feat called Mystic Accuracy

Benefit: You deal additional damage when attacking with mystic bolts equal to half of your Intelligence modifier (minimum +1), and you can apply the Deadly Aim, Piranha StrikeSTLC and Power Attack feat to attacks made with them even if they are touch attacks (due to the piercing bolts class feature). If you have the Clustered ShotsUC feat, you can total the damage from all hits before applying an opponent’s energy resistance.